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Light-burned magnesia powder is calcined magnesia from magnesite, brucite and magnesium hydroxide extracted from seawater or brine at about 800-1000 C, which decomposes and discharges CO2 or H2O. It is also called light-burned magnesia, caustic magnesia or light-burned magnesia, commonly known as bitter soil powder. Light-burned magnesia powder has loose texture and high chemical activity. It can be used not only in the manufacture of magnesia cement, MAGNESITE Building materials, thermal insulation materials, etc., but also in the production of high-quality magnesia by two-step calcination method. When magnesite is heated, equiaxed periclase occurs at about 600 ~C, equiaxed periclase disappears at 650 ~C and non-equiaxed periclase occurs, and equiaxed periclase disappears completely at 850 ~C.
These periclase crystal lattices have high surface energy due to point defects and dislocations. The lattice of MgO is not much larger than that of the MgCO3 lattice group, so the inter-lattice pores are increased, the porosity is high, the specific surface area is large, and the activity is high. Light burnt magnesium powder is light yellow and light brown powder, the particle size is mostly below -100 mesh, the calcite crystal is very small (<3μm), the true specific gravity is 3.07~3.22, the accumulated bulk density is 0.8~1.2g/cm3, and the refractive index is 1.68. ~1.70, large lattice constant (α=0.4212), many lattice defects, crunchy texture, pore structure, large reactivity, easy solid phase reaction or sintering, and hardening with Mg(HO)2. Bonding ability.
The calcined magnesia powder calcined from magnesite has a volume shrinkage of about 5%; usually 3% to 5% of CO2 remains due to incomplete decomposition. The light burning temperature and light burning time of magnesite have a certain influence on the activity of light burned magnesium powder.
The magnesite was calcined at 600, 650, 700, 750, 800, 850 and 900 ° C, respectively, and the calcination temperatures of 700, 750 and 800 ° C in 15 to 90 minutes had no significant effect on the activity of the light burned magnesium powder; The effects of 600, 650, 850 and 900 °C on the activity were particularly significant. When calcined at 600 and 650 °C, the activity increased significantly with time; the activity at 850 and 900 °C calcined decreased with the prolongation of hydrocarbon burning time.